Before workers are permitted to access the tops of rolling stock (tank trucks, tank railroad cars, etc.), this work environment should be secured to reduce the likelihood of workers falling. This environment typically is secured with the aid of a cage that must be deployed surrounding the portion of the top of the rolling stock where the workers must perform their duties. Also typical of this environment is a gangway that has a distal end connected to the cage. The proximal end of the gangway is anchored at a secure location from which workers can walk across the gangway to the top of the rolling stock. The gangway is provided with hydraulic or pneumatic apparatus by which the gangway can be moved between an elevated storage position above the rolling stock to a lowered position even with the height of the top of the rolling stock.
In one type of these gangways such as disclosed in U.S. Pat. Nos. 5,042,612; 5,392,878 and 7,140,467, which are hereby incorporated herein by this reference for all purposes, a proximal end of the gangway can be carried on one or more stanchions that extend vertically from one respective end of the loading platform. The gangway rides up and down along the stanchions like an elevator car between a relatively elevated storage orientation with respect to the top of rolling stock and a relatively lowered operative orientation with respect to the top of rolling stock. In another type of these gangways such as disclosed in U.S. Pat. Nos. 4,679,657; 7,216,741 and 8,015,647, which are hereby incorporated herein by this reference for all purposes, a proximal end of each of the respective gangways is pivotally connected to one respective end of the loading platform and can be moved pivotally like a drawbridge between a relatively elevated storage orientation respect to the top of rolling stock and a relatively lowered operative orientation with respect to the top of rolling stock. As explained for example in U.S. Pat. No. 6,502,267, which is hereby incorporated herein by this reference for all purposes, hydraulic or pneumatic apparatus is employed to move the gangway between the raised storage orientation and the lowered deployed orientation. A fall protection cage is attached to the distal end of the gangway so that it can be positioned over the top of the rolling stock.
Additional hydraulic or pneumatic apparatus is employed to extend and retract a gangway extension platform from beneath the distal end of the gangway. The gangway extension platform is extended forward until positioned to reach the top of the rolling stock. The cage typically is provided with depending panels that afford additional fall protection by being adjustably pivotable depending on the size and orientation of the cage in relation to the size and configuration of the top of the rolling stock. Still further hydraulic or pneumatic apparatus is required to deploy and retract the cage's pivoting panels. Each of these pneumatically-powered or hydraulically-powered apparatus must be operated individually and in the proper sequence in order to ensure proper deployment of worker fall protection in this working environment. Otherwise, while one worker is manipulating one of these deployment apparatus, another worker may begin walking on the gangway and actually reach the working site before all of the fall protection equipment is fully deployed and thus inadvertently be placed at greater risk of falling without protection. Additionally, a failure of the hydraulic or pneumatic power source can leave the apparatus improperly positioned and/or configured, and thus unable to ensure the best conditions for worker safety. Accordingly, a need exists for apparatus that addresses these issues.
The tops of rolling stock typically are furnished with some sort of railing structure that runs the length and width of the area where workers are at risk of falling from the top of the rolling stock. Due to the variety of different configurations for such railing structures, the cage configuration must be placed so as to accommodate the railing structure in a way that secures fall protection for the workers performing tasks at the top of the rolling stock. Having personnel on hand who are sufficiently competent to manipulate the cages appropriately with respect to the environments where the loading stock is parked and with respect to the configuration of the various railing structures also poses problems. Less competent personnel take longer to deploy the cages, and securing personnel sufficiently competent to deploy the cages can delay the performance of the tasks and tie up loading sites while the requisite personnel are secured. Such delays add additional cost to the performance of these tasks. However, until this secure placement has been effected, workers should not be permitted access to the top of the rolling stock. Accordingly, a need exists for apparatus that addresses these issues.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate at least one presently preferred embodiment of the invention as well as some alternative embodiments. These drawings, together with the written description, serve to explain the principles of the invention but by no means are intended to be exhaustive of all of the possible manifestations of the invention.